Re: Why does the open and overdue invoices not equal the A/R summary?
It's possible that there are available credits that haven't link to the invoice. When this happens, it will be recorded as either an open or overdue invoices. To check for these transactions, you'll have to drill down the Accounts receivable aging detail report.
Here's how to do it:
Click the Reports tab.
Enter account in the search bar, then select Accounts receivable aging detail.
Filter the date range.
The available credits (negative) are shown on the AMOUNT column.
You have the option to either linked the transactions or delete them.
Know that you can also saved the same settings of your customized reports by memorizing them. I've added this article to help you do it: Memorize Report.
If there's anything else that I can help you with, just post them here. I'll make sure to have you covered.